Pesticides Compound Antibiotic Resistance

Antibiotic resistance is often pegged as a problem caused by the overuse of antibiotics — and this is a driving factor — but research suggests it may actually be only one piece to the puzzle. Environmental factors may be accelerating the rise of antibiotic resistance as well, particularly widely used herbicides like glyphosate (Roundup) and dicamba (Kamba).

Research from University of Canterbury researchers revealed that agrichemicals and antibiotics in combination increase the evolution of antibiotic resistance. In fact, bacteria may develop antibiotic resistance up to 100,000 times faster when they’re exposed to certain herbicides in the environment.1

“The combination of chemicals to which bacteria are exposed in the modern environment should be addressed alongside antibiotic use if we are to preserve antibiotics in the long term,” study author Jack Heinemann of the University of Canterbury, said in a news release.2

‘Like Trying to Put Out a Fire of Antibiotic Resistance With Gasoline’

The study found cases when exposure to herbicides made the antibiotics more toxic while at the same time increasing the antibiotic resistance. Heinemann explained why this is an alarming finding:

“We are inclined to think that when a drug or other chemical makes antibiotics more potent, that should be a good thing. But it also makes the antibiotic more effective at promoting resistance when the antibiotic is at lower concentrations, as we more often find in the environment … Such combinations can be like trying to put out the raging fire of antibiotic resistance with gasoline.”

The results suggest that herbicides enhance the ability of antibiotics to become antibiotic resistant and that such resistance may be acquired at rates much faster than those predicted in laboratory conditions. Previously, research by Heinemann and colleagues found that commonly used herbicides promote antibiotic resistance by priming pathogens to more readily become resistant to antibiotics.3

This includes Roundup (the actual formulation of Roundup, not just its active ingredient glyphosate in isolation), which was shown to increase the antibiotic-resistant prowess of E. coli and salmonella, along with dicamba and 2,4-D. Rodale News reported:4

"The way Roundup causes this effect is likely by causing the bacteria to turn on a set of genes that are normally off, [study author] Heinemann says. 'These genes are for 'pumps' or 'porins,' proteins that pump out toxic compounds or reduce the rate at which they get inside of the bacteria ...'

Once these genes are turned on by the herbicide, then the bacteria can also resist antibiotics. If bacteria were to encounter only the antibiotic, they would instead have been killed. In a sense, the herbicide is 'immunizing' the bacteria to the antibiotic ... This change occurs at levels commonly used on farm field crops, lawns, gardens and parks."

Further research by Heinemann and colleagues, published in the journal Microbiology, set out to determine what ingredients of the commercial herbicide formulations caused the antibiotic resistance effect, with results showing the active ingredients are to blame.5

“Active ingredients induced changes in antibiotic responses similar to those caused by complete formulations. This occurred at or below recommended application concentrations,” the researchers noted.

Why CAFOs May Be Hot Houses for Antibiotic Resistance

In the environment, it’s common for herbicides and antibiotics to be used simultaneously. “Herbicides are used in agriculture, where spray drift or walking through treated fields exposes farm livestock and pets, which may be on therapeutic or prophylactic antibiotics,” researchers wrote in PeerJ.6

Eighty percent of the antibiotics used in the U.S. are used by industrial agriculture for purposes of growth promotion and preventing diseases. And it’s already known that concentrated animal feeding operations (CAFOs) are breeding grounds for antibiotic-resistant disease. As far back as the 1970s, antibiotic-resistant organisms were detected in chickens eating feed supplemented with antibiotics.

The resistant organisms were not found in the farmers or the animals prior to the use of the antibiotic on the farm, but within five months of its introduction into poultry feed, more than 31 percent of fecal samples from farmworkers tested positive for antibiotic-resistant organisms, even though none had been treated with the drug.7

The concurrent use of herbicides in agriculture only adds to the likelihood of serious antibiotic resistance emerging from industrial farms. Researchers explained the glaring role of CAFOs in antibiotic resistance in Environmental Health Perspectives:8

“This prolonged use of antibiotics, especially at low levels, presents a risk of not killing the bacteria while promoting their resistance by selecting for resistant populations. The resistance genes can pass readily from one kind of bacteria to another. Thus, workers in the animal units may become colonized with resistant organisms and can pass them on to co-workers and family members or friends.

Consumers of meat may also become colonized through mishandling of raw meat or through insufficient cooking. Ultimately, these genes may pass into pathogens, and diseases that were formerly treatable will be capable of causing severe illness or death.”

What’s more, Heinemann and colleagues explained, is that most antibiotics ingested by animals are not metabolized but rather excreted. This waste is then applied to soil as a fertilizer, which may then be sprayed with herbicide. The antibiotic-resistant microbes may then be carried elsewhere by houseflies.

Honeybees, which are also exposed to herbicides while foraging, may then return to a hive that’s been treated with antibiotics, revealing far more avenues for the creation of antibiotic-resistant disease than have been realized. “Additionally,” the researchers said, “herbicides are used in urban environments for purposes like gardening and lawn care, including parks and roadsides.”9

Other Chemicals Could Also Increase Antibiotic Resistance

It’s believed that other chemicals in the environment may also increase resistance in microbes, much like herbicides. For instance, prescription medications other than antibiotics have also been found to encourage antibiotic-resistant gut bacteria, as have food emulsifiers.

With about 8 million chemical substances currently manufactured, it’s likely that some of them may also influence antibiotic resistance, but the U.S. Environmental Protection Agency (EPA) doesn’t regulate or test them for such effects — even among the 3,000 top-volume chemicals produced annually.10 As written in PeerJ:11

“Evidence that antibiotic resistance evolution is influenced by exposure of bacteria to a wide range of substances may require us to make changes in how we manage both antibiotics and other manufactured and widely distributed chemical products. This is because many facets of the extrinsic environment induce adaptive changes, a complexity frequently ignored in standard studies of resistance.

As our results show, complex effects of exposures to nontherapeutic chemicals may undermine strategies to preserve the effectiveness of antibiotics through altering just their use. To our knowledge, there has been no attempt to systematically test common chemicals to which pathogenic bacteria are chronically exposed for effects on antibiotic resistance.”

Reducing the Use of Antibiotics May Not Be Enough

Campaigns are underway to stop antibiotics overuse, both in human medicine and agriculture. And there’s little doubt that the long-term administration of low doses of antibiotics on CAFOs is a practice that should be stopped to protect antibiotics’ effectiveness. However, even that may not be enough to stop this looming public health disaster — unless the use of herbicides and other chemicals that affect antibiotic resistance is also curbed.

“[A]ntibiotic resistance may increase even if total antibiotic use is reduced, and new ones are invented, unless other environmental exposures are also controlled,” GM Watch reported.12 However, an estimated 7.7 billion pounds of pesticides are applied to crops each year globally, and that number is steadily increasing.13

Rather than acknowledging that pesticide usage is overkill, pesticide companies incentivize the use of more harmful chemicals to farmers by offering cash back for purchasing more chemicals. Meanwhile, a 2015 study found that integrated pest management (IPM) techniques reduced pesticide use while boosting crop yields in a meta-analysis of 85 sites in 24 countries.14

Some were even able to eliminate pesticide use entirely using techniques such as crop rotation and pheromone traps to capture insect pests. So there are ways to slash pesticide usage considerably, but for now it seems we’re heading steadily toward a post-antibiotic era:15

“Neither reducing the use of antibiotics nor discovery of new ones may prevent the post-antibiotic era. This is because bacteria may be exposed to other nonantibiotic chemicals that predispose them to evolve resistance to antibiotics more quickly. Herbicides are examples of some of the most common nonantibiotic formulations in frequent global use.

More research is necessary to see to what extend other different manufactured chemicals may contribute to this effect. Moreover, depending on how the manufactured chemicals are used, or how they move through the waste stream, there may be combinatorial effects caused by mixtures of different products.”

In the U.S., according to U.S. Centers for Disease Control and Prevention (CDC) data, every year at least 2 million Americans acquire drug-resistant infections and 23,000 die as a result.

Many others die from conditions that were complicated by antibiotic-resistant infections.16 Worldwide, 700,000 people die every year due to antibiotic-resistant disease, and it’s estimated that more people will be affected by it than cancer by 2050.17

Steps to Protect Yourself Against Antibiotic Resistant Disease

You can get involved in the campaign to reduce pesticide usage by actively seeking out and supporting organic, regenerative farmers, who have decided that avoiding chemical-treated seeds and excessive chemical spraying is essential to nurturing soil health, protecting the environment and growing nutritious food.

In addition, seek out sustainably sourced, antibiotic-free meat and other grass fed animal products, including looking for the American Grassfed Association (AGA) logo, which lets you know the animals were fed a lifetime diet of 100 percent forage, were raised on pasture (not in confinement) and were not treated with hormones or antibiotics. You can further help reduce your risk of being affected by antibiotic-resistant disease by:

Using antibiotics only when absolutely necessary — Antibiotics are typically unnecessary for most ear infections, and they do not work on viruses. They only work on bacterial infections and, even then, they're best reserved for more serious infections.

Taking an antibiotic unnecessarily will kill off your beneficial gut bacteria for no reason at all, which could actually make it more difficult for you to recover from your illness. If you do take a course of antibiotics, be sure to reseed your gut with healthy bacteria by eating fermented foods or taking a probiotic supplement.

As an all-around preventive measure, make sure your vitamin D level is optimized year-round, especially during pregnancy, along with vitamin K2. A number of other natural compounds can also help boost your immune system function to help rid you of an infection, including vitamin C, oil of oregano, garlic, Echinacea and tea tree oil.

Manuka honey can also be used for topical applications, as it’s effective against many bacteria, including some resistant varieties, such as MRSA.

Avoiding all antibacterial household products — This includes items such as antibacterial hand sanitizers and wipes, toothpaste, deodorants and detergents, as these too promote antibiotic resistance.

Properly washing your hands with warm water and plain soap, to prevent the spreading of bacteria — Be particularly mindful of washing your hands and kitchen surfaces after handling raw meats from CAFOs, as about half of all meat sold in grocery stores around the U.S. is likely to be contaminated with potentially dangerous bacteria.